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Even familiar animals indulge in strange activities.

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Cats from far and wide are irresistably drawn to a seemingly insignificant plant.

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In the presence of catnip, they do the unexpected.

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They not only eat its flowers; they rub, sniff, and chew its leaves.

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[Purring]

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Cats are strangely addicted to this fragrant herb.

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They return for a fix of its heady scent again and again.

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Its aromatic oils make them frisky and playful.

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As they fall deeper under its influence, their mood changes in other odd ways.

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As well as rolling around apparently in ecstasy, they chase imaginary mice.

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This odd behavior is triggered by chemicals resembling those in tomcat urine.

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Courting females writhe in this provocative way. But strangely catnip affects both sexes.

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Cats even inherit this sensitivity.

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Three-quarters are affected in some way.

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This weird journey shows how natural chemicals influence animal behavior and reveals much about ourselves.